Papers by Keyword: Mesophase Pitch

Abstract: Two dimensional carbon/carbon composites (2D C/C) were prepared by the low temperature-heat molding technique with PAN based carbon fabric as reinforcement and pre-oxidation mesophase pitch as matrix precursors. The effect of pre-oxidation for mesophase pitch on microstructure and flexural strength of 2D C/C composites has been evaluated using polarized light optical microscope, scanning electron microscope and three-point bending tests. As pre-oxidation temperature rising, the softening point of mesophase pitch increases, oxygen-containing functional groups increases as well, QI (quinoline insoluble) content increases significantly. The flexural strength dependence of pre-oxidation temperature has been studied and correlated with microstructure of 2D C/C composites. Results show that flexural strength increase when the pre-oxidation temperature rising, and meet its peak at 140°C, reached 44.7514MPa.

Abstract: C/C composites were prepared by low temperature and hot pressure moulding process from T300 carbon fibre and medium temperature pitch(MTP) or MP with nematic liquid crystalline. The effect of the content of carbon fibre and different proportion of MTP to MP on interlaminar bonding strength (ILBS) of C/C composites was investigated. C/C composites were characterized by ILBS test and scanning electron microscope. Results showed that the ILBS increased with the increase of the content of carbon fibre and proportion of MTP. When the content of carbon fibre was 60.5%, the ILBS of composites prepared from MP reached up to 1.498MPa, and to 3.031MPa from MTP.

Abstract: Carbon foam with relatively high compressive strength and high porosity was prepared from a mixture of mesophase pitch and Si particles by foaming and carbonization. The influence of Si content on the microstructures and properties of the carbon foam was studied. Results show that the pore number decreases and the strut thickness increases with an increasing of Si content. In addition, bulk density also increases with increasing Si content but the porosity decreases. Si addition to the mesophase pitch reduces the number of microcracks on the cell wall of the carbon foam remarkably which results in an increase of compressive strength for the carbon foams. Compressive strengths improve by 46%, 176% and 339% at Si additions of 30%, 40% and 50% (wt %), respectively. Carbon foam with a relatively high compressive strength of 24.6 MPa and a porosity of 61% are obtained when 50 wt% Si is added.

Abstract: The rheological behaviors of mesophase pitch containing different contents (0, 1.0, 2.0 wt%) of multi-wall carbon nanotubes (MWNTs) were studied by using ARES cone-plate rheometer. The dynamic response of mesophase pitch containing MWNTs was different from that of pure mesophase pitch due to the MWNTs as a suspension in viscous pitch. The dynamic viscosity increased with increasing the amount of MWNTs, which is a clear evidence of the interruption of MWNTs in mesophase pitch. Also, the phase angle result indicates that mesophase pitch containing MWNT had less elastic nature than pure mesophase pitch.

Abstract: Mesophase pitch (MPP) has a high carbon yield and excellent graphitizability, compared with commercial coal tar pitch (CTP), which make it suitable for the preparation of C/C composites. In this paper, two MPP were prepared by heat-treatment of two coal tar pitches (CTP and modified coal tar pitch (MCTP)) in the presence of nitrogen. Elemental analysis and FTIR were used to monitor the change of chemical structures of MPP transition from CTP and MCTP. The pyrolysis behaviors of CTP and MCTP were studied by means of thermal analysis (TG and DSC). The morphologies of MPP were inspected by optical microscope. The structures of the MPP were characterized by XRD. The results show that there are more alkyl functional groups existing in CTP and MCTP than in MPP, and MPP has a higher C/H ratio than CTP and MCTP, which indicate MPP formation predominantly polycondense aromatic and release the alkyl functional groups. An endothermic band due to volatilize light compounds around 290 °C, two exothermic peaks at 430°C and 490 °C were characteristic of polymerization reactions, exothermic peaks of MCTP are higher than that of CTP because the former has a higher reaction active for its more alkyl side chain. The optical texture of MPP from CTP is mosaics texture, while from the MCTP is flow domains texture. (002), (101) peaks of graphite occur on XRD patterns, the peaks of MPP from MCTP are higher and narrower than MPP from CTP, which indicates the former is more graphitizability than the latter.